1. Field of the Invention
The present invention relates to an inkjet head cleaning apparatus, an image recording apparatus and an inkjet head cleaning method, and more particularly to technology for cleaning a liquid ejection surface of an inkjet head.
2. Description of the Related Art
As a general image recording apparatus, it is suitable to use an inkjet recording apparatus, which forms a desired image on a recording medium by ejecting and depositing colored inks from a plurality of nozzles provided in an inkjet head. If the inkjet head is operated for a long period of time, adhering matter such as solidified ink or paper dust from the recording medium, and the like, adhere to the nozzle surface. In particular, if adhering matter becomes attached to the vicinity of the nozzles and the nozzle apertures, this gives rise to deflection of the ejection direction of the ink ejected from the nozzles, or reduction in the ejection volume, and so on. An inkjet recording apparatus is composed in such a manner that cleaning of the nozzle surface is carried out appropriately.
Japanese Patent Application Publication No. 2000-094703 discloses a cleaning apparatus which applies a cleaning liquid in a non-contact fashion to an inkjet head, by rotating an application roller having a cylindrical shape which is immersed in the cleaning liquid.
An inkjet recording apparatus which employs a drum conveyance method whereby a recording medium is held on the outer circumferential surface of a round cylindrical conveyance drum and conveyed on the outer circumferential surface of the conveyance drum, as a device for conveying the recording medium, is disposed obliquely to the horizontal plane in such a manner that the recording head faces the outer circumferential surface of the conveyance drum.
A cleaning apparatus 260 shown in FIG. 11 has a cleaning liquid application unit 262 which holds a cleaning liquid 261 on a surface 262A facing the nozzle surface 272A of the inkjet head (head) 272, and employs a method which brings the cleaning liquid 261 into contact with the nozzle surface 272A to apply cleaning liquid to the nozzle surface 272A. FIG. 11 is a diagram of a full line type head 272 viewed from the breadthways direction thereof, and the direction passing through the plane of the drawing is the lengthwise direction of the head 272.
When the nozzle surface 272A of the head 272 that is arranged obliquely to the horizontal plane is cleaned by using the above-described cleaning apparatus 260, then the cleaning liquid 261 collects on the inclined lower side 262C rather than being held on the inclined upper side 262B, and it is difficult to apply the cleaning liquid uniformly to the nozzle surface 272A. For example, if a composition is adopted in which a device (e.g., a nozzle) for emitting cleaning liquid is arranged on a surface facing the nozzle surface 272A and the cleaning liquid is emitted in the form of a shower by using a high pressure, then it is possible to form a coating layer of the cleaning liquid over the whole of the surface on which the cleaning liquid is emitted. However, this system is not desirable since it needs supplying the cleaning liquid of over the necessary amount.
The cleaning apparatus described in Japanese Patent Application Publication No. 2000-094703 consumes a large quantity of the cleaning liquid in order to provide the application roller with a coating layer of a certain thickness of the cleaning liquid.